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Biomedical subjects

B Dupas

Publications and source records attributed to B Dupas.

At least 37 records · Page 2Linked to original sources
PubMed2001

Contrast-enhanced MR imaging of experimental acute tubular necrosis.

PURPOSE: To demonstrate the involvement of the various renal structures in acute tubular necrosis (ATN). MATERIAL AND METHODS: In 15 rats, using a T1-/T2-weighted sequence, either gadodiamide alone, or gadodiamide in combination with sprodiamide (a susceptibility agent) were used to enhance the various anatomical substrates of the kidney. The results were compared to those of pathological verification. RESULTS: Experimentally induced ATN of the rat kidney causes profound changes in the medulla, leaving the cortex largely intact. The difference between the normal cortex and the partially necrotic outer medulla, on the one hand, and the papillary region, was significantly enhanced with the combination, whereas a larger region composed of the inner and outer medulla was enhanced after the gadolinium chelate alone. CONCLUSION: The results varied considerably between the two procedures; the double contrast demonstrated a clear difference between the inner and outer medulla, and the gadolinium chelate alone demonstrated a clear difference between the medulla and the cortex. These results demonstrated a clear difference in the compartmentalization between the inner and outer medullary regions, providing complementary information about the pathological condition of the kidney.

Animals↗
PubMed2001

Hepatocyte-mediated transport to the bile of AMI-HS, a particulate contrast agent.

RATIONALE AND OBJECTIVES: The elimination of hepatocyte-directed particulate contrast agents has not been studied in the same detail as particles eliminated mainly by the mononuclear phagocyte system. The aim of the present study was to elucidate the fate of these particles by a multidisciplinary approach. METHODS: After intravenous injection of AMI-HS particles directed to the hepatocytes, rats were killed and cytological studies, by both electron microscopy and histochemistry, and spectroscopic studies of the bile were performed. The data were compared with a dynamic magnetic resonance study of the heart and liver. RESULTS: The particles were rapidly cleared from the blood by Kupffer cells and hepatocytes and then found first in the vascular and later in the biliary pole of the hepatocytes. After 24 hours, a relaxometric characterization of the bile showed the presence of unchanged particles in the bile. CONCLUSIONS: These results show the capacity of the liver to excrete unchanged AMI-HS particles directly into the bile.

Animals↗
PubMed2000

Interruption of the inferior vena cava with azygos termination associated with congenital absence of portal vein.

The authors report an exceptional and well-documented case of interruption of the retrohepatic segment of the inferior vena cava with an "azygos continuation", combined with absence of the portal vein. The only known combination of congenital anomalies of the inferior vena cava and the portal vein was that of an "azygos continuation" and a preduodenal portal vein. The double interruption, portal and inferior caval, may be associated with a disturbance of preferential flows induced by the left umbilical thrust. According to hemodynamic theory, the left umbilical flow is the determining factor in organogenesis of the portal vein and the retrohepatic segment of the inferior vena cava.

Abnormalities, Multiple↗
PubMed2000

[MRI-cholangiopancreatography characteristics of cystic pancreatic tumors].

STUDY AIM: The purpose was to assess the value of MR cholangiopancreatography (MRCP) to evaluate the diagnosis and surgical resectability of pancreatic cystic tumors. PATIENTS AND METHODS: For MRCP, thick RARE and thin HASTE heavily T2-weighted sequences were performed with a 1.5 Tesla MR unit in 42 patients. Diffusion-weighted echo-planar sequences were performed in 16 patients. Surgical and histopathological correlation was obtained in 15 patients. RESULTS: MRCP detected all cystic lesions of the pancreas: 15 intraductal papillary mucinous tumors, 10 serous cystadenomas, 2 benign mucinous cystadenomas, 1 solid pseudopapillary tumor and 14 small cystic lesions (less than 2 cm) with no clinical signs. MRCP provided complete visualization of the pancreatic duct, showed excrescences within the dilated main or branch pancreatic ducts, identified microlacunar mixed and macrolacunar patterns, as well as septa, communications and stenosis, without contrast agent. MRCP did not characterize serous or mucinous cystic lesions. Specific diagnostic criteria of the various types of intraductal papillary mucinous tumors were noted (main duct, branch duct and combined types) and illustrated with the imaging findings necessary for accurate differential diagnosis. CONCLUSION: MRCP is a useful noninvasive and essential method in preoperative staging of cystic tumors of the pancreas; it is a reasonable alternative to endoscopic retrograde cholangiopancreatography and endosonography, as it provides the necessary information for treatment: surgical decision and/or follow-up.

Bile Ducts↗
PubMed2000

[Diaphragmatic excursion after inter-sternocleidomastoid block depending on the site of the injection].

OBJECTIVE: To evaluate the incidence of the hemidiaphragmatic paresis after inter Sterno-Cleido-Mastoid (inter-SCM) block. STUDY DESIGN: Prospective, comparative, single blind study. PATIENTS: 16 patients ASA I-II. METHODS: The diaphragmatic paresis was measured by a radiologist unaware of the technique used and operated side. It was determined by the diaphragmatic excursion (DE) on double-exposure chest radiography, obtained preoperatively and postoperatively (DE-pre, DE-post) for the ipsilateral and controlateral side of the inter-SCM block. All the patients were given 20 mL 0.5% bupivacaine plus 20 mL 2% lidocaine both with epinephrine. These anesthetics were injected via the stimuling needle or via the catheter after opacified radiological control of the catheter position. The patients were divided into 2 groups. Group 1: injection via the needle after eliciting flexion of fingers, or via a catheter into infraclavicular position; group 2: injection via the needle after eliciting contraction of deltoid, or elbow flexion, or via a supraclavicular catheter. RESULTS: All the patients had satisfactory block. The ipsilateral DE was decreased after injection of anesthetics in group 2 (P < 0.001) while it remained unchanged in group 1. CONCLUSION: The diaphragmatic paresis is avoidable with the inter-SCM block if and only if the anesthetic solution is injected via the needle after stimulating flexion of fingers or via a catheter into infraclavicular position.

Adult↗
PubMed2000

[Evaluation of a new sequence of magnetic resonance cholangio-pancreatography in thick cut and one shot acquisition].

OBJECTIVES: To assess the accuracy and reproducibility of a new magnetic resonance cholangiopancreatography sequence (MRCP), using long echo time and "single shot" acquisition (providing high-contrast thick slices: 20 mm or more), in the morphological analysis of the biliary tree and pancreatic ducts. METHODS: Fifty four patients with biliary and/or pancreatic disease were investigated with MRCP "single shot" thick slices. Biliary ducts were explored with MRCP "single shot", coronal and oblique coronal 20 mm thick slices on a 256 x 256 matrix. Natives pictures were reviewed by three independent radiologists, from three different institutions. MRCP results were compared with reference examinations in 54 cases (direct biligraphy methods: 54, CT scan: 11, endoscopic ultrasonography: 6, surgery: 6). RESULTS: For detection of bile duct dilatation, the agreement of MRCP "single shot" thick slices was more than 96% (Kappa > 0.92) and the inter-observer agreement was excellent (Kappa=0.92). For detection of biliary tree and/or pancreatic duct obstruction, MRCP "single shot" thick slice sensitivity was above 89% and specificity was 75%. The malignant nature of the lesions was determined with a sensitivity of 100% and a specificity of 92%. MRCP "single shot" thick slices could not differentiate pancreatic carcinomas from distal main bile duct cholangiocarcinomas. MRCP "single shot" thick slices did not detect small stones ( 3 mm) of the common bile duct. CONCLUSION: The excellent sensitivity, specificity and inter-observer agreement of MRCP "single shot" thick slices can be used to limit invasive imaging methods in the diagnosis of extrahepatic cholestasis.

Adult↗
PubMed1999

Electron microscopy study of intrahepatic ultrasmall superparamagnetic iron oxide kinetics in the rat. Relation with magnetic resonance imaging.

Ultrasmall superparamagnetic iron oxide (USPIO) contrast agents for use in magnetic resonance imaging (MRI) are currently undergoing clinical evaluation. However, the images observed and the kinetic profiles obtained differ from one agent to another. In this study, BD IX rats received an intravenous penis injection of the USPIO contrast agents AMI-HS and AMI-227. A cytologic study of the liver was performed, and the data obtained were compared with those of MRI. Images acquired in light microscopy, transmission electron microscopy, microanalysis and electron diffraction provided data on the cell categories involved in the processing of these contrast agents, the importance and modalities of each category relative to this processing, and the modalities of agent elimination. AMI-HS was rapidly removed from the bloodstream by Kupffer's cells and hepatocytes and then eliminated through bile ducts. AMI-227 remained much longer in the blood compartment since it was processed very slowly by endothelial and Kuppfer's cells in the near absence of hepatocytic participation and thus of elimination by the bile ducts. These results allowed us to base our interpretation of MRI sequences on cytologic observations.

Animals↗
PubMed1999

Gadolinium-enhanced MR imaging of normal renal transplants. An evaluation of a T1-weighted dynamic echo-planar sequence.

PURPOSE: To evaluate the potential usefulness of dynamic MR with echoplanar imaging (EPI) in assessing the renal function in patients with renal allografts. MATERIAL AND METHODS: Using a T1-weighted sequence, EPI was performed after injection of a Gd-chelate in 17 patients with normally functioning renal allografts. Time-intensity curves were plotted from the signal intensity (SI) measurements of the cortex and the medulla. RESULTS: The pattern of corticomedullar differentiation (CMD) observed after contrast enhancement was divided into four phases using the T1-EPI. After a rapid decrease in the SI of cortical structures, and a subsequent return to precontrast levels, a gradual fall in the SI of the medulla was observed. The average time between the two periods of signal loss was 60 s. CONCLUSION: This study illustrated the potential use of dynamic T1-EPI to demonstrate contrast-induced CMD in renal allografts.

Adult↗
PubMed1999

[MR cholangiopancreatography in choledochal cysts].

PURPOSE: To assess the value of MR cholangiopancreatography (MRCP) in the diagnosis and preoperative evaluation of choledochal cysts. MATERIAL AND METHODS: Five patients (aged between 6 days and 28 years) were investigated by MRCP, referred for ultrasonographic detection of a bile duct dilatation or a cystic structure, of antenatal diagnosis (1 case), for jaundice or abdominal pain (3 cases) or in late follow-up of a choledochal cyst surgery. Two endoscopic-ultrasonographic studies were performed. The five patients underwent surgery without preoperative biliary cholangiography. MRCP was performed using a HASTE sequence in frontal, oblique, axial planes (1,5 Tesla MR unit). RESULTS: MRCP allowed to confirm choledochal cyst, helps to specify the anatomical type (2 type I, 3 type II), detects choledocholithiasis (3 cases). Anatomic correlation was perfect. MRCP allowed to exclude gastrointestinal duplication. Anomalous junction of the pancreaticobiliary duct was found in one case. CONCLUSION: MRCP diagnoses choledochal cysts, specifies type, helps surgery and can avoid endoscopic retrograde cholangiography or endoscopic sonographic examinations especially for children. It may find an anomalous junction of the pancreaticobiliary duct.

Adolescent↗
PubMed1998

Interleukin-2/sodium butyrate treatment cures rats bearing liver tumors after acquired 5-fluorouracil resistance.

We studied the effect of immunotherapy using recombinant interleukin-2 (rIL-2) in combination with a differentiating agent, sodium butyrate (NaBut), on experimental 5-fluorouracil (5-FU)-resistant liver metastasis from colorectal cancer in rats. For this purpose, we used direct liver injection of 5-FU resistant cells, PRObRI, in syngeneic BDIX rats to establish liver tumors. The growth of liver metastasis was followed before and after NaBut/rIL-2 treatment by magnetic resonance imaging (MRI). The presence of liver tumors was checked by MRI 7 days after tumor cell injection. Evaluable rats were then assigned randomly to a control and an experimental group. The different treatments were started on day 10 and administered intraperitoneally (i.p.). Combined NaBut/rIL-2 treatment followed by MRI on days 56 and 91 was shown both to significantly reduce the growth of liver tumors and to prevent extrahepatic spread. In addition, NaBut/rIL-2 treatment induced a complete regression in 50% of the rats which remained free of disease.

Animals↗
PubMed1998

Peripheral blood stem cell transplantation as front-line therapy in patients aged 61 to 65 years: a pilot study.

The aim of the present trial was to investigate the feasibility of high-dose therapy followed by autologous peripheral blood stem cell transplantation (PBSCT) as a component of front-line treatment in patients with disseminated intermediate- and high-grade non-Hodgkin's lymphoma (NHL) aged 61-65 years. From October 1993 to June 1996, 14 consecutive patients entered this single-center prospective pilot trial. Patients were five males and nine females, median age 63 (range 61-65). The first-line treatment consisted of three courses of CHOP therapy. Patients achieving either a partial response (PR) or a complete response (CR) after initial therapy were eligible for PBSCT, while those with refractory or progressive disease were not autografted but included in the feasibility study in an intent-to-treat analysis. Of the 14 patients, 11 achieved either a CR (one) or a PR (10) after three courses of CHOP while the three patients with no response were not autografted and subsequently died of progressive disease. PBSC collection was feasible in responding patients after G-CSF priming (10 microg/kg/day for 6 days). Conditioning therapy was the BEAM protocol. All patients engrafted after PBSCT. The median time to granulocyte (>0.5 x 10(9)/l) and platelet recovery (>25 x 10(9)/l) was 12 (range 9-18) and 13 days (range 7-22), respectively. No toxic deaths VOD or IP were observed. Four of the 11 responding patients relapsed 2, 7, 9 and 12 months after PBSCT, respectively, and all died from progressive disease. Overall, 7/14 patients are alive and free from disease, 16-43 months after initial diagnosis (median 28). The actuarial overall survival is 45.7 %, and the actuarial event-free survival is 50% at 3.5 years. This study shows the feasibility of high-dose therapy and PBSCT in patients with intermediate- or high-grade disseminated NHL aged 61-65 years. Such patients should not be excluded from trials evaluating the role of ASCT as part of initial treatment for disseminated and histologically aggressive NHL.

Aged↗
PubMed1998

Synergistic effects of relaxation and susceptibility in differentiation between compartmentalized and noncompartmentalized tissues.

RATIONALE AND OBJECTIVES: This study illustrates the synergistic effects of relaxation- and susceptibility-based contrast enhancement. Using a combination of gadolinium (Gd) and dysprosium (Dy) complexes and a sequence capable of taking advantage of the particular relaxation behavior of this combination, the difference between compartmentalized and noncompartmentalized regions was significantly enhanced. METHODS: Magnetic resonance imaging of the rat kidney was performed before and immediately after the administration of a combination of Gd and Dy chelates (Gd-DTPA-BMA and Dy-DTPA-BMA). RESULTS: The signal intensity (SI) of the renal parenchyma was reduced by 85%, whereas the collecting tubes had a 100% increase of their SI as demonstrated by a short repetition time (600 msec), long echo time (50 msec), and spin-echo sequence. CONCLUSIONS: The high R2* effect, specific to the compartmentalized tissues, associated with the moderately high R1 and R2 developed in the remaining areas, results in an important improvement in tissue differentiation, which potentially is useful for the evaluation of pathological changes as in tubular necrosis.

Animals↗
PubMed1998

Early intensive therapy with autologous stem cell transplantation in high-risk Hodgkin's disease: long-term follow-up in 35 cases.

Thirty-five adult patients with high-risk HD (HD) defined by (1) Ann Arbor stage IV or bulky nodal disease (tumor/thorax ratio > 0.45) and (2) no or partial response (PR) (< 75%) to the initial 3 courses of ABVD, received an early intensive therapy with autologous stem cell transplantation (ASCT). Thirty patients were considered as partial responders and 5 as refractory to initial chemotherapy. Conditioning regimen consisted of chemotherapy alone (CBV in 11 patients before 1993, BEAM in 13 patients since 1993) followed by adjuvant radiotherapy: 40 Gy) on the initial sites of bulky disease, or 12 Gy total body irradiation plus 120 mg/kg cyclophosphamide in 11 patients with disseminated extra-nodal disease. All 30 patients in PR at the time of ASCT experienced prolonged complete remission (CR). One patient died in CR from an acute myocardial infarction 48 months after ASCT. Four out of the 5 patients with refractory disease at the time of ASCT experienced rapid progression of HD leading to death in 3 cases. After 6 years of CR post-ASCT, the last refractory patient died of myelodysplastic syndrome diagnosed 2 years after intensive therapy. With a median follow-up for surviving patients of 51 months (range: 11-111), the cumulative probability of 8-year overall survival is 75.6% for the entire group of patients, 94.1% for the chemosensitive ones, and 0% for the primary refractory (P < .0001). The cumulative probability of 8-year event-free survival is 79.9% for the entire group of patients, 94.1% for the chemosensitive ones, and 0% for the primary refractory (P < .0001). We conclude that early intensive therapy with ASCT is feasible in patients with high-risk HD and induces a high cure rate in chemosensitive patients. In primary refractory patients, new therapeutic approaches are warranted.

Adolescent↗
PubMed1998

Diagnosis of brain death using two-phase spiral CT.

PURPOSE: The purpose of this study was to determine the utility of spiral CT in the diagnosis of brain death. METHODS: Spiral CT was evaluated prospectively in 14 brain-dead patients and in 11 healthy subjects. A two-phase protocol was used. Twenty seconds after intravenous injection of a nonionic iodinized contrast medium, the CT table was drawn through the gantry at a rate of 10 mm/s while scanning was in progress. The second scanning phase was started automatically a mean of 54 seconds later, using the same parameters. Opacification or absence of opacification of carotid, vertebral, and basilar arteries and intracerebral veins was ascertained for each image in both phases. The diagnosis of brain death was confirmed by elecroencephalography (n = 7), angiography (n = 5), or both (n = 2). Statistical analysis with the Fisher exact test enabled us to compare the brain-dead patients with the healthy control subjects. RESULTS: In brain death, the pericallosal and terminal arteries of the cortex did not opacify during the two phases of spiral CT, whereas the superficial temporal arteries were always visible. The internal cerebral veins, the great cerebral vein, and the straight sinus did not opacify, whereas the superior ophthalmic veins were visible on both sides 13 times. For each vessel type, specificity was 100% for nonvascular opacification criteria on the right and left sides. CONCLUSION: Two-phase spiral CT can demonstrate the absence of intracerebral blood flow in brain death.

Adolescent↗